1. Field of the Invention
The invention relates to the field of managed communication networks and more particularly diagnostic devices for determining the cause of problems occurring within such networks.
2. Description of the Prior Art
Problems occurring in managed communication networks can have many different causes. The main causes include, for example, power outages, broken connections, breakdowns or malfunctions of network equipments (or the components constituting them), and the integration of a new or old version of a network equipment (or a component constituting it) that is not entirely compatible with the remainder of the network.
In the present context, the expression “network equipment” refers to a combination of hardware and software.
A certain number of diagnostic devices (or tools) have been proposed for determining the causes of problems. Certain of these devices use techniques based on programming in object-oriented languages and/or rules-based languages, possibly managed by a rules engine. This applies in particular to the event correlation expert (ECXpert) device, devices from ILOG that use a programmable rules engine for diagnosis, Network Node Manager® version 6.4 devices, Network Node Manager Extended Topology® version 2.0 devices from Hewlett Packard, the Fault Detective for Data Communications (FDDC)® device from Agilent, and the TAC® device from CISCO.
ALCATEL also offers a diagnostic device based on Bayesian probabilistic theory and used to define rules for refining hypotheses on the basis of concepts of additional evidence and background information, which lead to numbers each representing the probability that a hypothesis is true and used to construct Bayesian networks (also known as Bayesian diagrams) defining test operations associated with statistical or probabilistic weights.
The main drawback of the above diagnostic devices is that they use static diagnostic models, i.e. models whose characteristics are fixed when they are designed and therefore cannot be adapted (or in the best case scenario only very partially adapted) to evolution of the resources of most networks, as much from the point of view of the hardware (or the versions thereof) as from the point of view of the software (or the versions thereof), or to evolution of the traffic in the network. This is a result of the fact that the diagnostic models are constructed from a knowledge base that is based on expert knowledge and that is rarely adapted to all the specific hardware and software and/or to all the combinations of hardware and/or software, and which additionally is at best representative of only what is known in the art at the time it was designed.
U.S. Pat. No. 6,076,083 proposes a solution for adapting diagnostic models, but merely as a function of experience acquired in their use. This solution is therefore unable to take account of the evolution of the managed communication network, and is therefore inadequate.
It is, of course, always possible to design new diagnostic models adapted to each evolution of the network, but this is particularly costly and necessitates a certain design time during which new causes of problems occurring within a network cannot be diagnosed correctly.
The object of the invention is to improve on the situation of there being no prior art diagnostic device that is entirely satisfactory.